Re: [Detnet] Regarding the model for Active OAM packet
Loa Andersson <loa@pi.nu> Fri, 21 September 2018 10:55 UTC
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To: Mach Chen <mach.chen@huawei.com>, Greg Mirsky <gregimirsky@gmail.com>
Cc: DetNet WG <detnet@ietf.org>, János Farkas <Janos.Farkas@ericsson.com>, "detnet-chairs@ietf.org" <detnet-chairs@ietf.org>
References: <F73A3CB31E8BE34FA1BBE3C8F0CB2AE29267092D@dggeml530-mbs.china.huawei.com> <CA+RyBmX29+Q9y3dXM-PqYm-Nu8KtjYZDs6a-fh_rW5hacSpyRg@mail.gmail.com> <F73A3CB31E8BE34FA1BBE3C8F0CB2AE292672CBB@dggeml530-mbs.china.huawei.com> <d4e45e7d-1001-be64-9ff0-f9ea9a882b77@pi.nu> <F73A3CB31E8BE34FA1BBE3C8F0CB2AE292673B40@dggeml530-mbs.china.huawei.com> <1e141c08-421a-3698-ac5f-02b597d978ea@pi.nu> <F73A3CB31E8BE34FA1BBE3C8F0CB2AE292677F9A@dggeml530-mbs.china.huawei.com> <cdfbdcba-af1b-4ab6-9c7d-bd2960af7f01@pi.nu> <F73A3CB31E8BE34FA1BBE3C8F0CB2AE29267813A@dggeml530-mbs.china.huawei.com>
From: Loa Andersson <loa@pi.nu>
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Date: Fri, 21 Sep 2018 18:55:25 +0800
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Subject: Re: [Detnet] Regarding the model for Active OAM packet
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Mach, inline please On 2018-09-21 18:31, Mach Chen wrote: > Hi Loa, > > New ACH type is fine, this is also needed for DetNet OAM, IMHO. The crucial here is how to "cheat" the replication/elimination nodes that an OAM packet is a "normal" DetNet packet, then they can replicate/eliminate the OAM packets as normal DetNet packets. Otherwise, it needs to introduce additional replication/elimination processing for the DetNet OAM packets. > > To support this, I suggest to use ACH without GAL (of cause, a new ACH-type) for DetNet OAM (as bellow) and the "reserved" field carries sequence number information, the "ACH" can be considered as the d-CW by the replication/elimination nodes. > +----------+ > |S-Label | > +----------+ > |ACH | > +----------+ > | Payload| > +----------+ > what info do a node use to understand that the ACH is an ACH?? /Loa > If GAL is used ( the stack as below), additional processing has to be introduced at the replication/elimination nodes, because they have to parse GAL+ACH to decide how to process. That means, the OAM packets will have different replication/elimination process from the normal DetNet packets. > > +----------+ > |S-Label | > +----------+ > |GAL | > +----------+ > |ACH | > +----------+ > | Payload| > +----------+ > > Best regards, > Mach > >> -----Original Message----- >> From: Loa Andersson [mailto:loa@pi.nu] >> Sent: Friday, September 21, 2018 4:49 PM >> To: Mach Chen <mach.chen@huawei.com>; Greg Mirsky >> <gregimirsky@gmail.com> >> Cc: DetNet WG <detnet@ietf.org>; János Farkas >> <Janos.Farkas@ericsson.com>; detnet-chairs@ietf.org >> Subject: Re: [Detnet] Regarding the model for Active OAM packet >> >> Mach, >> >> Admittedly I'm not up to speed on DetNet OAM, but ..... >> >> The ACH is specified like this: >> >> 0 1 2 3 >> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 >> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >> |0 0 0 1|Version| Reserved | Channel Type | >> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >> >> you can define 65k ACH-types, what stops you from defining a ACH channel >> type for DetNet OAM, then define that the structure of the following octets >> in a way that you see fit (like (yes I'm inventing as I type, more thoughts >> should go into to this): >> >> 0 1 2 3 >> 0123 45678901 234567890123 45678901 >> +----+--------+------------+--------+ >> | R | LEN | relevant info | >> +----+--------+------------+--------+ >> |0000| d-CW | >> +----+--------+------------+--------+ >> | more relevant info | >> +----+--------+------------+--------+ >> >> >> What is that I'm missing? >> >> /Loa >> >> On 2018-09-21 14:22, Mach Chen wrote: >>> Hi Loa, >>> >>> Can you clarify how a new ACH-type can address the problem? >>> >>> Best regards, >>> Mach >>> >>>> -----Original Message----- >>>> From: Loa Andersson [mailto:loa@pi.nu] >>>> Sent: Thursday, September 20, 2018 6:14 PM >>>> To: Mach Chen <mach.chen@huawei.com>; Greg Mirsky >>>> <gregimirsky@gmail.com> >>>> Cc: DetNet WG <detnet@ietf.org>; János Farkas >>>> <Janos.Farkas@ericsson.com>; detnet-chairs@ietf.org >>>> Subject: Re: [Detnet] Regarding the model for Active OAM packet >>>> >>>> Mach, >>>> >>>> I'd like Stewart or Matthew to look at this, but as I understand it >>>> it is possible to define a new ACH-type that can do exactly what you want. >>>> >>>> /Loa >>>> >>>> On 2018-09-20 17:58, Mach Chen wrote: >>>>> Loa, >>>>> >>>>> GAL is just an OAM indicator, the problem here is that when do >>>>> DetNet >>>> OAM, the d-CW will replaced by ACH or by GAL+ACH. No matter which >> way >>>> is used, to support the replication or elimination, there has to be a >>>> sequence number filed. But ACH (as its current defined) does not have >> such a field. >>>>> >>>>> My suggestion is to use the reserved field of ACH to carry sequence >>>> number of OAM packet, and for those replication or elimination >>>> nodes, they do not have to differentiate whether a packet is OAM >>>> packet or a normal packet, they could just treat the right 28 bits of >>>> the ACH as the sequence number ( or treat the ACH as the d-CW), then >>>> both OAM and replication/elimination can be supported. >>>>> >>>>> Best regards, >>>>> Mach >>>>> >>>>>> -----Original Message----- >>>>>> From: detnet [mailto:detnet-bounces@ietf.org] On Behalf Of Loa >>>>>> Andersson >>>>>> Sent: Thursday, September 20, 2018 3:21 PM >>>>>> To: Mach Chen <mach.chen@huawei.com>; Greg Mirsky >>>>>> <gregimirsky@gmail.com> >>>>>> Cc: DetNet WG <detnet@ietf.org>; János Farkas >>>>>> <Janos.Farkas@ericsson.com>; detnet-chairs@ietf.org >>>>>> Subject: Re: [Detnet] Regarding the model for Active OAM packet >>>>>> >>>>>> Mach, >>>>>> >>>>>> If I understand you correctly this is for an LSP in an MPLS >>>>>> network, can you help me understand why GAL does not enough. >> Given >>>>>> that there might be some minor extensions to GAL because of >>>>>> replication and >>>> elimination. >>>>>> >>>>>> /Loa >>>>>> >>>>>> On 2018-09-19 14:31, Mach Chen wrote: >>>>>>> Hi Greg, >>>>>>> >>>>>>> Indeed, there is no DetNet Associated Channel defined in >>>>>>> draft-ietf-detnet-dp-sol-mpls for now, I think there should be. I >>>>>>> also assume that PW ACH will be used for DetNet OAM. >>>>>>> >>>>>>> Assume that PW ACH will be used for DetNet OAM and the reserved >>>>>>> filed of the PW ACH will be used to carry sequence number for OAM >>>> packet. >>>>>>> But >>>>>>> for PREF, a tricky way is to treat the “Version”+ “Reserved” + >>>>>>> ”Channel type” as the Sequence number, the replication or >>>>>>> elimination nodes do not need to differentiate whether it is a >>>>>>> d-CW or a >>>> PW ACH . >>>>>>> This way, OAM can be supported without additional processing and >>>> states. >>>>>>> >>>>>>> 0 1 2 >>>>>>> 3 >>>>>>> >>>>>>> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 >>>>>>> 8 9 >>>>>>> 0 >>>>>>> 1 >>>>>>> >>>>>>> >>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >>>>>>> >>>>>>> |0 0 0 1|Verion | Reserved | Channel Type >>>>>>> | >>>>>>> >>>>>>> >>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >>>>>>> >>>>>>> Regarding sequence number, there are two ways to generate the >>>>>> sequence >>>>>>> number IMHO: 1) generated by the edge node, but it may need to >>>>>>> configure the start number, or 2) copied from the application-flow >>>>>>> (if there is). If the WG agree with this, the model can be updated >>>>>>> reflect this. >>>>>>> >>>>>>> Best regards, >>>>>>> >>>>>>> Mach >>>>>>> >>>>>>> *From:*Greg Mirsky [mailto:gregimirsky@gmail.com] >>>>>>> *Sent:* Wednesday, September 19, 2018 11:29 AM >>>>>>> *To:* Mach Chen <mach.chen@huawei.com> >>>>>>> *Cc:* János Farkas <Janos.Farkas@ericsson.com>; DetNet WG >>>>>>> <detnet@ietf.org>; detnet-chairs@ietf.org >>>>>>> *Subject:* Re: Regarding the model for Active OAM packet >>>>>>> >>>>>>> Hi Mach, >>>>>>> >>>>>>> thank you for your attention to my comment and the most expedient >>>>>> response. >>>>>>> >>>>>>> I don't find the DetNet Associated Channel defined in >>>>>>> draft-ietf-detnet-dp-sol-mpls and thus I assumed that OAM packets >>>>>>> that follow the data packet encapsulation defined in that draft >>>>>>> use PW ACH as defined in section 5 RFC 4385: True, it includes 8 >>>>>>> bits-long Reserved field that may be defined as OAM Sequence >>>>>>> Number but that >>>>>> had >>>>>>> not been discussed. One is certain, existing nodes do not check >>>>>>> the Reserved field. And without a field to hold the sequence >>>>>>> number, PREF will not handle the OAM packets. Another question, >>>>>>> additional processing and amount of state introduced in the fast >>>>>>> path by the fact that OAM's Sequence Number will have different >>>>>>> length and location in d-CW (differentiating cases by the first nibble). >>>>>>> >>>>>>> Now, if we step back from DetnNet in MPLS data plane >>>>>>> encapsulation, why the control-word, as I understand, is >>>>>>> configurable? I think that the Sequence Number is not >>>>>>> configurable, nor the first nibble. What do you think? >>>>>>> >>>>>>> Regards, >>>>>>> >>>>>>> Greg >>>>>>> >>>>>>> On Tue, Sep 18, 2018 at 7:48 PM Mach Chen >> <mach.chen@huawei.com >>>>>>> <mailto:mach.chen@huawei.com>> wrote: >>>>>>> >>>>>>> Hi Greg, >>>>>>> >>>>>>> The MPLS DetNet header is defined as below: >>>>>>> >>>>>>> grouping mpls-detnet-header { >>>>>>> description >>>>>>> "The MPLS DetNet encapsulation header information."; >>>>>>> leaf service-label { >>>>>>> type uint32; >>>>>>> mandatory true; >>>>>>> description >>>>>>> "The service label of the DetNet header."; >>>>>>> } >>>>>>> leaf control-word { >>>>>>> type uint32; >>>>>>> mandatory true; >>>>>>> description >>>>>>> "The control word of the DetNet header."; >>>>>>> } >>>>>>> } >>>>>>> >>>>>>> Although do not consider Active OAM when design the above >>>>>>> mpls-denet-header, seems that it can cover Active OAM case as >> well. >>>>>>> No matter a normal DetNet packet or an Active OAM packet, there >>>>>>> should be a CW field, just as defined above. >>>>>>> >>>>>>> For normal DetNet packets, the CW is the d-CW as defined in the >>>>>>> draft-ietf-detnet-dp-sol-mpls. >>>>>>> >>>>>>> For OAM packets, the CW is the "DetNet Associated Channel". >>>>>>> >>>>>>> Best regards, >>>>>>> Mach >>>>>>> >>>>>>> >>>>>>> > -----Original Message----- >>>>>>> > From: detnet [mailto:detnet-bounces@ietf.org >>>>>>> <mailto:detnet- >>>>>> bounces@ietf.org>] On Behalf >>>>>>> Of Greg Mirsky >>>>>>> > Sent: Wednesday, September 19, 2018 3:17 AM >>>>>>> > To: János Farkas <Janos.Farkas@ericsson.com >>>>>> <mailto:Janos.Farkas@ericsson.com>> >>>>>>> > Cc: DetNet WG <detnet@ietf.org <mailto:detnet@ietf.org>>; >>>>>>> detnet- >>>>>> chairs@ietf.org >>>>>>> <mailto:detnet-chairs@ietf.org> >>>>>>> > Subject: Re: [Detnet] WG adoption poll >>>>>>> draft-geng-detnet-conf- >>>> yang >>>>>>> > >>>>>>> > Hi Janos, et. al, >>>>>>> > the mpls-detnet-header container is based on the solution >>>> described in >>>>>>> > draft-ietf-detnet-dp-sol-mpls. Analysis of active SFC OAM >>>>>>> in the >>>>>> proposed >>>>>>> > MPLS data plane solution in draft-mirsky-detnet-oam points >>>>>>> to the >>>>>> potential >>>>>>> > problem as result the fact that OAM packet doesn't include >>>>>>> d-CW. I >>>>>> believe >>>>>>> > that this question should be discussed and, if we agree on >>>>>>> the >>>> problem >>>>>>> > statement, properly resolved. Until then, I do not support >>>>>>> the adoption >>>>>> of >>>>>>> > the model that may not be capable to support active OAM. >>>>>>> > >>>>>>> > Regards, >>>>>>> > Greg >>>>>>> > On Tue, Sep 18, 2018 at 12:03 PM Janos Farkas >>>>>> <Janos.Farkas@ericsson.com <mailto:Janos.Farkas@ericsson.com>> >>>>>>> > wrote: >>>>>>> > > >>>>>>> > > Dear all, >>>>>>> > > >>>>>>> > > This is start of a two week poll on making >>>>>>> > > draft-geng-detnet-conf-yang-04 a working group document. >>>>>>> Please >>>>>> send >>>>>>> > > email to the list indicating "yes/support" or "no/do not >>>> support". If >>>>>>> > > indicating no, please state your reservations with the >>>> document. If >>>>>>> > > yes, please also feel free to provide comments you'd like to see >>>>>>> > > addressed once the document is a WG document. >>>>>>> > > >>>>>>> > > The poll ends Oct 3. >>>>>>> > > >>>>>>> > > Thanks, >>>>>>> > > János and Lou >>>>>>> > > >>>>>>> > > _______________________________________________ >>>>>>> > > detnet mailing list >>>>>>> > > detnet@ietf.org <mailto:detnet@ietf.org> >>>>>>> > > https://www.ietf.org/mailman/listinfo/detnet >>>>>>> > >>>>>>> > _______________________________________________ >>>>>>> > detnet mailing list >>>>>>> > detnet@ietf.org <mailto:detnet@ietf.org> >>>>>>> > https://www.ietf.org/mailman/listinfo/detnet >>>>>>> >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> detnet mailing list >>>>>>> detnet@ietf.org >>>>>>> https://www.ietf.org/mailman/listinfo/detnet >>>>>>> >>>>>> >>>>>> -- >>>>>> >>>>>> >>>>>> Loa Andersson email: loa@pi.nu >>>>>> Senior MPLS Expert >>>>>> Bronze Dragon Consulting phone: +46 739 81 21 64 >>>>>> >>>>>> _______________________________________________ >>>>>> detnet mailing list >>>>>> detnet@ietf.org >>>>>> https://www.ietf.org/mailman/listinfo/detnet >>>>> _______________________________________________ >>>>> detnet mailing list >>>>> detnet@ietf.org >>>>> https://www.ietf.org/mailman/listinfo/detnet >>>>> >>>> >>>> -- >>>> >>>> >>>> Loa Andersson email: loa@pi.nu >>>> Senior MPLS Expert >>>> Bronze Dragon Consulting phone: +46 739 81 21 64 >> >> -- >> >> >> Loa Andersson email: loa@pi.nu >> Senior MPLS Expert >> Bronze Dragon Consulting phone: +46 739 81 21 64 > _______________________________________________ > detnet mailing list > detnet@ietf.org > https://www.ietf.org/mailman/listinfo/detnet > -- Loa Andersson email: loa@pi.nu Senior MPLS Expert Bronze Dragon Consulting phone: +46 739 81 21 64
- [Detnet] Regarding the model for Active OAM packet Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen